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-rw-r--r--fs/hfs/bitmap.c412
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diff --git a/fs/hfs/bitmap.c b/fs/hfs/bitmap.c
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+/*
+ * linux/fs/hfs/bitmap.c
+ *
+ * Copyright (C) 1996-1997 Paul H. Hargrove
+ * This file may be distributed under the terms of the GNU Public License.
+ *
+ * Based on GPLed code Copyright (C) 1995 Michael Dreher
+ *
+ * This file contains the code to modify the volume bitmap:
+ * search/set/clear bits.
+ *
+ * "XXX" in a comment is a note to myself to consider changing something.
+ *
+ * In function preconditions the term "valid" applied to a pointer to
+ * a structure means that the pointer is non-NULL and the structure it
+ * points to has all fields initialized to consistent values.
+ */
+
+#include "hfs.h"
+
+/*================ Global functions ================*/
+
+/*
+ * hfs_vbm_count_free()
+ *
+ * Description:
+ * Count the number of consecutive cleared bits in the bitmap blocks of
+ * the hfs MDB starting at bit number 'start'. 'mdb' had better
+ * be locked or the indicated number of blocks may be no longer free,
+ * when this functions returns!
+ * Input Variable(s):
+ * struct hfs_mdb *mdb: Pointer to the hfs MDB
+ * hfs_u16 start: bit number to start at
+ * Output Variable(s):
+ * NONE
+ * Returns:
+ * The number of consecutive cleared bits starting at bit 'start'
+ * Preconditions:
+ * 'mdb' points to a "valid" (struct hfs_mdb).
+ * Postconditions:
+ * NONE
+ */
+hfs_u16 hfs_vbm_count_free(const struct hfs_mdb *mdb, hfs_u16 start)
+{
+ hfs_u16 block_nr; /* index of the current bitmap block */
+ hfs_u16 bit_nr; /* index of the current bit in block */
+ hfs_u16 count; /* number of bits found so far */
+ hfs_u16 len; /* number of bits found in this block */
+ hfs_u16 max_block; /* index of last bitmap block */
+ hfs_u16 max_bits; /* index of last bit in block */
+
+ /* is this a valid HFS MDB? */
+ if (!mdb) {
+ return 0;
+ }
+
+ block_nr = start / HFS_BM_BPB;
+ bit_nr = start % HFS_BM_BPB;
+ max_block = (mdb->fs_ablocks + HFS_BM_BPB - 1) / HFS_BM_BPB - 1;
+
+ count = 0;
+ while (block_nr <= max_block) {
+ if (block_nr != max_block) {
+ max_bits = HFS_BM_BPB;
+ } else {
+ max_bits = mdb->fs_ablocks % HFS_BM_BPB;
+ }
+
+ len=hfs_count_zero_bits(hfs_buffer_data(mdb->bitmap[block_nr]),
+ max_bits, bit_nr);
+ count += len;
+
+ /* see if we fell short of the end of this block */
+ if ((len + bit_nr) < max_bits) {
+ break;
+ }
+
+ ++block_nr;
+ bit_nr = 0;
+ }
+ return count;
+}
+
+/*
+ * hfs_vbm_search_free()
+ *
+ * Description:
+ * Search for 'num_bits' consecutive cleared bits in the bitmap blocks of
+ * the hfs MDB. 'mdb' had better be locked or the returned range
+ * may be no longer free, when this functions returns!
+ * XXX Currently the search starts from bit 0, but it should start with
+ * the bit number stored in 's_alloc_ptr' of the MDB.
+ * Input Variable(s):
+ * struct hfs_mdb *mdb: Pointer to the hfs MDB
+ * hfs_u16 *num_bits: Pointer to the number of cleared bits
+ * to search for
+ * Output Variable(s):
+ * hfs_u16 *num_bits: The number of consecutive clear bits of the
+ * returned range. If the bitmap is fragmented, this will be less than
+ * requested and it will be zero, when the disk is full.
+ * Returns:
+ * The number of the first bit of the range of cleared bits which has been
+ * found. When 'num_bits' is zero, this is invalid!
+ * Preconditions:
+ * 'mdb' points to a "valid" (struct hfs_mdb).
+ * 'num_bits' points to a variable of type (hfs_u16), which contains
+ * the number of cleared bits to find.
+ * Postconditions:
+ * 'num_bits' is set to the length of the found sequence.
+ */
+hfs_u16 hfs_vbm_search_free(const struct hfs_mdb *mdb, hfs_u16 *num_bits)
+{
+ hfs_u16 block_nr; /* index of the current bitmap block */
+
+ /* position and length of current portion of a run */
+ hfs_u16 cur_pos, cur_len;
+
+ /* position and length of current complete run */
+ hfs_u16 pos=0, len=0;
+
+ /* position and length of longest complete run */
+ hfs_u16 longest_pos=0, longest_len=0;
+
+ void *bitmap; /* contents of the current bitmap block */
+ hfs_u16 max_block; /* upper limit of outer loop */
+ hfs_u16 max_bits; /* upper limit of inner loop */
+
+ /* is this a valid HFS MDB? */
+ if (!mdb) {
+ *num_bits = 0;
+ hfs_warn("hfs_vbm_search_free: not a valid MDB\n");
+ return 0;
+ }
+
+ /* make sure we have actual work to perform */
+ if (!(*num_bits)) {
+ return 0;
+ }
+
+ max_block = (mdb->fs_ablocks+HFS_BM_BPB-1) / HFS_BM_BPB - 1;
+
+ /* search all bitmap blocks */
+ for (block_nr = 0; block_nr <= max_block; block_nr++) {
+ bitmap = hfs_buffer_data(mdb->bitmap[block_nr]);
+
+ if (block_nr != max_block) {
+ max_bits = HFS_BM_BPB;
+ } else {
+ max_bits = mdb->fs_ablocks % HFS_BM_BPB;
+ }
+
+ cur_pos = 0;
+ do {
+ cur_len = hfs_count_zero_bits(bitmap, max_bits,
+ cur_pos);
+ len += cur_len;
+ if (len > longest_len) {
+ longest_pos = pos;
+ longest_len = len;
+ if (len >= *num_bits) {
+ goto search_end;
+ }
+ }
+ if ((cur_pos + cur_len) == max_bits) {
+ break; /* zeros may continue into next block */
+ }
+
+ /* find start of next run of zeros */
+ cur_pos = hfs_find_zero_bit(bitmap, max_bits,
+ cur_pos + cur_len);
+ pos = cur_pos + HFS_BM_BPB*block_nr;
+ len = 0;
+ } while (cur_pos < max_bits);
+ }
+
+search_end:
+ *num_bits = longest_len;
+ return longest_pos;
+}
+
+
+/*
+ * hfs_set_vbm_bits()
+ *
+ * Description:
+ * Set the requested bits in the volume bitmap of the hfs filesystem
+ * Input Variable(s):
+ * struct hfs_mdb *mdb: Pointer to the hfs MDB
+ * hfs_u16 start: The offset of the first bit
+ * hfs_u16 count: The number of bits
+ * Output Variable(s):
+ * None
+ * Returns:
+ * 0: no error
+ * -1: One of the bits was already set. This is a strange
+ * error and when it happens, the filesystem must be repaired!
+ * -2: One or more of the bits are out of range of the bitmap.
+ * -3: The 's_magic' field of the MDB does not match
+ * Preconditions:
+ * 'mdb' points to a "valid" (struct hfs_mdb).
+ * Postconditions:
+ * Starting with bit number 'start', 'count' bits in the volume bitmap
+ * are set. The affected bitmap blocks are marked "dirty", the free
+ * block count of the MDB is updated and the MDB is marked dirty.
+ */
+int hfs_set_vbm_bits(struct hfs_mdb *mdb, hfs_u16 start, hfs_u16 count)
+{
+ hfs_u16 block_nr; /* index of the current bitmap block */
+ hfs_u16 u32_nr; /* index of the current hfs_u32 in block */
+ hfs_u16 bit_nr; /* index of the current bit in hfs_u32 */
+ hfs_u16 left = count; /* number of bits left to be set */
+ hfs_u32 *bitmap; /* the current bitmap block's contents */
+
+ /* is this a valid HFS MDB? */
+ if (!mdb) {
+ return -3;
+ }
+
+ /* is there any actual work to be done? */
+ if (!count) {
+ return 0;
+ }
+
+ /* are all of the bits in range? */
+ if ((start + count) > mdb->fs_ablocks) {
+ return -2;
+ }
+
+ block_nr = start / HFS_BM_BPB;
+ u32_nr = (start % HFS_BM_BPB) / 32;
+ bit_nr = start % 32;
+
+ /* bitmap is always on a 32-bit boundary */
+ bitmap = (hfs_u32 *)hfs_buffer_data(mdb->bitmap[block_nr]);
+
+ /* do any partial hfs_u32 at the start */
+ if (bit_nr != 0) {
+ while ((bit_nr < 32) && left) {
+ if (hfs_set_bit(bit_nr, bitmap + u32_nr)) {
+ hfs_buffer_dirty(mdb->bitmap[block_nr]);
+ return -1;
+ }
+ ++bit_nr;
+ --left;
+ }
+ bit_nr=0;
+
+ /* advance u32_nr and check for end of this block */
+ if (++u32_nr > 127) {
+ u32_nr = 0;
+ hfs_buffer_dirty(mdb->bitmap[block_nr]);
+ ++block_nr;
+ /* bitmap is always on a 32-bit boundary */
+ bitmap = (hfs_u32 *)
+ hfs_buffer_data(mdb->bitmap[block_nr]);
+ }
+ }
+
+ /* do full hfs_u32s */
+ while (left > 31) {
+ if (bitmap[u32_nr] != ((hfs_u32)0)) {
+ hfs_buffer_dirty(mdb->bitmap[block_nr]);
+ return -1;
+ }
+ bitmap[u32_nr] = ~((hfs_u32)0);
+ left -= 32;
+
+ /* advance u32_nr and check for end of this block */
+ if (++u32_nr > 127) {
+ u32_nr = 0;
+ hfs_buffer_dirty(mdb->bitmap[block_nr]);
+ ++block_nr;
+ /* bitmap is always on a 32-bit boundary */
+ bitmap = (hfs_u32 *)
+ hfs_buffer_data(mdb->bitmap[block_nr]);
+ }
+ }
+
+
+ /* do any partial hfs_u32 at end */
+ while (left) {
+ if (hfs_set_bit(bit_nr, bitmap + u32_nr)) {
+ hfs_buffer_dirty(mdb->bitmap[block_nr]);
+ return -1;
+ }
+ ++bit_nr;
+ --left;
+ }
+
+ hfs_buffer_dirty(mdb->bitmap[block_nr]);
+ mdb->free_ablocks -= count;
+
+ /* successful completion */
+ hfs_mdb_dirty(mdb->sys_mdb);
+ return 0;
+}
+
+/*
+ * hfs_clear_vbm_bits()
+ *
+ * Description:
+ * Clear the requested bits in the volume bitmap of the hfs filesystem
+ * Input Variable(s):
+ * struct hfs_mdb *mdb: Pointer to the hfs MDB
+ * hfs_u16 start: The offset of the first bit
+ * hfs_u16 count: The number of bits
+ * Output Variable(s):
+ * None
+ * Returns:
+ * 0: no error
+ * -1: One of the bits was already clear. This is a strange
+ * error and when it happens, the filesystem must be repaired!
+ * -2: One or more of the bits are out of range of the bitmap.
+ * -3: The 's_magic' field of the MDB does not match
+ * Preconditions:
+ * 'mdb' points to a "valid" (struct hfs_mdb).
+ * Postconditions:
+ * Starting with bit number 'start', 'count' bits in the volume bitmap
+ * are cleared. The affected bitmap blocks are marked "dirty", the free
+ * block count of the MDB is updated and the MDB is marked dirty.
+ */
+int hfs_clear_vbm_bits(struct hfs_mdb *mdb, hfs_u16 start, hfs_u16 count)
+{
+ hfs_u16 block_nr; /* index of the current bitmap block */
+ hfs_u16 u32_nr; /* index of the current hfs_u32 in block */
+ hfs_u16 bit_nr; /* index of the current bit in hfs_u32 */
+ hfs_u16 left = count; /* number of bits left to be set */
+ hfs_u32 *bitmap; /* the current bitmap block's contents */
+
+ /* is this a valid HFS MDB? */
+ if (!mdb) {
+ return -3;
+ }
+
+ /* is there any actual work to be done? */
+ if (!count) {
+ return 0;
+ }
+
+ /* are all of the bits in range? */
+ if ((start + count) > mdb->fs_ablocks) {
+ return -2;
+ }
+
+ block_nr = start / HFS_BM_BPB;
+ u32_nr = (start % HFS_BM_BPB) / 32;
+ bit_nr = start % 32;
+
+ /* bitmap is always on a 32-bit boundary */
+ bitmap = (hfs_u32 *)hfs_buffer_data(mdb->bitmap[block_nr]);
+
+ /* do any partial hfs_u32 at the start */
+ if (bit_nr != 0) {
+ while ((bit_nr < 32) && left) {
+ if (!hfs_clear_bit(bit_nr, bitmap + u32_nr)) {
+ hfs_buffer_dirty(mdb->bitmap[block_nr]);
+ return -1;
+ }
+ ++bit_nr;
+ --left;
+ }
+ bit_nr=0;
+
+ /* advance u32_nr and check for end of this block */
+ if (++u32_nr > 127) {
+ u32_nr = 0;
+ hfs_buffer_dirty(mdb->bitmap[block_nr]);
+ ++block_nr;
+ /* bitmap is always on a 32-bit boundary */
+ bitmap = (hfs_u32 *)
+ hfs_buffer_data(mdb->bitmap[block_nr]);
+ }
+ }
+
+ /* do full hfs_u32s */
+ while (left > 31) {
+ if (bitmap[u32_nr] != ~((hfs_u32)0)) {
+ hfs_buffer_dirty(mdb->bitmap[block_nr]);
+ return -1;
+ }
+ bitmap[u32_nr] = ((hfs_u32)0);
+ left -= 32;
+
+ /* advance u32_nr and check for end of this block */
+ if (++u32_nr > 127) {
+ u32_nr = 0;
+ hfs_buffer_dirty(mdb->bitmap[block_nr]);
+ ++block_nr;
+ /* bitmap is always on a 32-bit boundary */
+ bitmap = (hfs_u32 *)
+ hfs_buffer_data(mdb->bitmap[block_nr]);
+ }
+ }
+
+
+ /* do any partial hfs_u32 at end */
+ while (left) {
+ if (!hfs_clear_bit(bit_nr, bitmap + u32_nr)) {
+ hfs_buffer_dirty(mdb->bitmap[block_nr]);
+ return -1;
+ }
+ ++bit_nr;
+ --left;
+ }
+
+ hfs_buffer_dirty(mdb->bitmap[block_nr]);
+ mdb->free_ablocks += count;
+
+ /* successful completion */
+ hfs_mdb_dirty(mdb->sys_mdb);
+ return 0;
+}
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